The Clinical Significance Of Panoramic Oncogene Detection Of Plasma And Tissue From Patients With Gastric Cancer And Colorectal Cancer

Objective:By extracting plasma ctDNA samples and tumor tissue samples from surgical patients with gastric cancer and colorectal cancer,Illumina HiSeq 4000 high-throughput sequencing platform was used for panoramic gene testing to analyze the clinical value of the results of gene testing.Methods:Selecting patients with confirmed gastric cancer or colorectal cancer who had radical surgical resection in our hospital from September 2018 to March 2019.The Illumina HiSeq 4000 high-throughput sequencing platform was used for the panoramic genetic testing of plasma samples and tumor tissue samples,so as to detect the specific gene mutation and mutation abundance of each patient.Results:1.High-throughput exon sequencing of 425 gene was successfully performed on 30 blood samples and 24 tissue samples by using the scheme of target capture combined with next-generation sequencing.Through bioinformatics analysis,tumor-specific mutations were detected in 24 tissue samples(100%),and tumor-specific mutations were detected in 20 blood samples(66.6%).2.A total of 115 tumor-specific mutant genes and 124 mutant types were detected,with an average mutation abundance of 17.7%.3.The genes with high mutation frequency were TP53(21/24,87.5%),KRAS(10/24,41.7%),APC(13/24,54.2%),PIK3CA(5/24,20.8%)and PTEN(4/24,16.7%).In KRAS mutation loci,there were 4 cases(40.0%)of G12 D,2 cases(20.0%)of G12 A,2 cases(20.0%)of G12 S,1 case(10.0%)of G12 V and 1 case(10.0%)of A146 T.4.The detection rate of TP53 gene in stage Ⅰ,Ⅱ and Ⅲ patients was stage I(2/2,100.0%),stage Ⅱ(6/7,85.7%)and stage Ⅲ(13/15,86.7%),respectively.The detection rate of gastric cancer(4/4,100.0%),right colon cancer(2/4,50.0%),left colon cancer(3/3,100.0%),sigmoid colon cancer(3/4,75.0%),rectal cancer(9/9,100.0%).The detection rate of moderately differentiated carcinoma(12/14,85.7%)and of moderately-and low-differentiated carcinoma(9/10,90.0%).There were no significant differences in clinical stage(P=0.269 > 0.05),tumor location(P=0.083 > 0.05),and tumor differentiation degree(P=1.000 > 0.05).There was no statistically significant difference in the TP53 gene mutation rate between different clinical stages(P=0.854 > 0.05),tumor location(P=0.092 > 0.05),and tumor differentiation degree(P=0.754 > 0.05).TP53 has a high detection rate in gastric cancer,left hemicolon cancer and rectal cancer.5.The detection rates of KRAS gene in stage Ⅰ,Ⅱ and Ⅲ patients were stage I(0/2,0%),stage Ⅱ(4/7,57.1%)and stage Ⅲ(6/15,40%),respectively.The detection rate of gastric cancer(1/4,25.0%),right colon cancer(3/4,75.0%),left colon cancer(0/3,0%),sigmoid colon cancer(2/4,50.0%),rectal cancer(4/9,44.4%).The detection rate of moderately differentiated carcinoma(5/14,35.7%)and moderately-poorly differentiated carcinoma(5/10,50.0%).There was no statistically significant difference in KRAS gene mutation abundance between different stages(P=0.477 > 0.05),tumor location(P=0.520 > 0.05),and tumor differentiation degree(P=0.578 > 0.05).There was no significant difference in KRAS gene mutation rate between different clinical stages(P=0.344 > 0.05),tumor location(P=0.334 > 0.05)and tumor differentiation degree(P=0.484 > 0.05).6.The detection rates of APC gene in stage Ⅰ,Ⅱ and Ⅲ patients were stage I(0/2,0%),stage Ⅱ(3/7,42.9%)and stage Ⅲ(10/15,66.7%),respectively.The detection rate of gastric cancer(0/4,0%),right colon cancer(3/4,75.0%),left colon cancer(0/3,0%),sigmoid colon cancer(4/4,100%),rectal cancer(6/9,66.7%).The overall detection rate was 65%.The detection rate of moderately differentiated carcinoma(8/14,57.1%)and moderately-and low-differentiated carcinoma(5/10,50.0%).Two patients with a family history of colorectal cancer had higher mutation abundance of APC(34.4% and 23.0%).There were no statistically significant differences in clinical stage(P=0.472 > 0.05),tumor location(P=0.121 > 0.05),and tumor differentiation degree(P=0.099 > 0.05).There was no significant difference in APC gene mutation rate between different clinical stages(P=0.160 > 0.05)and tumor differentiation degree(P=0.729 > 0.05).There were significant differences in tumor APC mutation rates at different locations(P=0.012 < 0.05).7.All patients had a total of 7 patients with high TMB,and 6 patients also had KRAS mutation.KRAS,TP53 or APC mutations were found in one patient,but he was microsatellite instability(MSI-H).KRAS gene and TP53 gene mutations were correlated with tumor mutation burden.8.Blood samples were collected from 3 of the 24 patients before,during and after surgery to detect ctDNA mutations,among which,ctDNA mutations were not detected in 1 patient before,during and after surgery,indicating an early stage.Two other patients in the preoperative and intraoperative blood plasma samples detected ctDNA mutations,including individual genotype intraoperative mutation abundance improved compared with preoperative mutations,in most of the plasma to detect the mutation in the detection of plasma samples are less than 7 days corresponding mutations,but one plasma samples detected postoperatively in patients with preoperative,intraoperative and tissue samples of undetected genetic mutations-ABCB1.Conclusions:1.ctDNA and tumor tissue mutations can be detected by panoramic gene detection to understand the specific mutation genes and mutation sites of each patient.This information is conducive to the selection of chemotherapy drugs,targeted drugs,prognosis,drug resistance and other aspects of evaluation,which is conducive to the development of precision medicine and can benefit patients.2.The phased genetic testing of ctDNA is conducive to the dynamic follow-up of the cancer treatment process,and can indicate whether the operation will cause the spread of cancer.3.Tumor location is related to the mutation rate of APC gene.4.KRAS gene and TP53 gene mutations are correlated with tumor mutation burden.